1. Field of the Invention
This invention relates generally to sound systems in multimedia personal computers and in particular is directed to a graphic audio equalizer with audio controls and graphic display mounted on a front panel for installation in a drive bay of the case of a personal computer system.
2. Background of the Invention
Personal computers or PCs are now common household and workplace appliances and have evolved into multimedia systems capable of processing digitally encoded sound files along with other data files, i.e. capable of both video and audio output. PCs are typically organized as a mother board, which is a large printed circuit board mounted in a case, a number of daughter cards each mounted in a slot connector of the mother board, one or more data storage drives each mounted in a drive bay of the case, and a common power supply also mounted in the case. The mother board carries the central processor, BIOS read-only memory, random access memory, and various peripheral integrated circuits which perform data input/output functions for the central processor. Various auxiliary systems are arranged on separate printed circuit boards which have a series of edge connectors along one edge of the circuit card, and the card is installed by inserting the card edge in a slot connector on the mother board of the PC. For example, the sound card converts digitally encoded audio to analog sound signals capable of driving the computers loudspeakers. Other cards frequently installed in slots on the mother board include video output systems and communications modems. Some daughter cards require inputs and outputs external to the computer system. These are normally provided as input or output connectors mounted on a metal bracket which is affixed to the rear edge of the card. When the card is installed in a slot connector on the mother board, this bracket aligns with and closes a rear slot opening in the computer case . The input/output connectors are on the side of the bracket facing the outside of the case and are accessible for making electrical connections with mating connectors on external cables of various types. This system organization provides much flexibility in the configuration and assembly of a PC because components can be chosen according to the needs, preferences and budget of each user.
The present direction in evolution of personal computers is towards complete audio-visual entertainment and information systems fully integrated with traditional computer data processing and data communications capability. For example, a CD-ROM drive may be used for installing software on a magnetic disk of the PC, for graphic display of reference materials including stored text and images on the video monitor of the PC, and for listening to music on conventional audio CDs (compact discs). Television and radio tuners are available on daughter cards which along with appropriate operating software permit viewing of television broadcasts on the computer monitor and listening to radio broadcasts through the PC's sound card and loudspeakers. In other words, the equipment which traditionally constituted the home entertainment center is being integrated with the personal computer. This trend in turn has created a need for PC audio handling capabilities which more closely approach the high quality sound reproduction of traditional separate audio component systems, in order to replace the rather utilitarian sound systems now commonly found in PCs.
One such audio component is the graphic equalizer, which divides the audio spectrum into narrow frequency bands, typically ten or twelve bands. On the front panel of the equalizer are provided a series of slide controls, each of which can be moved up or down from a neutral center position to raise or lower the sound level for a particular frequency band. When all of the slide controls are so adjusted their relative positions on the front panel of the equalizer provides a graphic display representative of the overall frequency response of the equalizer over the entire audio spectrum, typically from 20 Hz to 20 kHz.
Graphic equalizers are useful for tailoring or shaping the frequency response of an audio system to compensate for shortcomings in one or more of the components, for peculiarities in the listening environment, or simply to suit someone's personal listening preferences. For instance, the presence or absence of upholstery or draperies in a listening room can greatly affect the quality of sound reproduction, which can be balanced by appropriate adjustment of the equalizer controls. Sophisticated control over sound reproduction is possible, as when compensating for subtle resonances in a particular room which affect narrow sound frequency bands. Peaks and dips in a loudspeaker's frequency response can be similarly equalized to more closely approach an ideal flat frequency over the entire audio spectrum. The graphic equalizer allows the listener to overcome many limitations of an audio setup.
Audio equalizers available for use with personal computers generally have been of two types. One is in the form of a daughter card installed internally in the computer's case on a slot of the mother board and is controlled via software which provides a graphic display on the video monitor of the computer. The other known type is essentially a conventional stand-alone graphic equalizer which is connected to the outputs of the computer sound card with audio cables.
Neither approach is entirely satisfactory. The internal card mounted software controlled equalizers take up a slot on the mother board which may not be available or may be needed for other more important uses. Software control of the equalizer forces the computer operator to call up the software utility on the video screen whenever adjustment is desired, an inconvenience which may necessitate exiting another previously running software application. And while the equalizer display is off-screen, which is normally the case, the operator has no information of the equalizer's settings. The stand-alone equalizers, on the other hand, increase clutter in the form of yet another box with a power cord which has to plugged into an A.C. outlet and interconnecting cables between the equalizer and the PC.
A continuing need exists for an audio equalizer which overcomes the aforementioned shortcomings.